Systems and methods for drilling in high temperature environments using optical fiber communication

ABSTRACT

A drilling system includes a lower drill string and an upper drill string. The lower drill string includes a drill bit, a drive system coupled to the drill bit, at least one lower drill pipe coupled to the drive system, and a sensor system disposed in the at least one lower drill pipe. The sensor system includes one or more sensors and a first connector coupled to the one or more sensors. The upper drill string is coupled to the lower drill string and includes one or more upper drill pipes. The upper drill string also includes a MWD/LWD electronics system coupled to the one or more upper drill pipes. The MWD/LWD electronics system includes an electronics component communicatively coupled to the first connector via a fiber optic cable. The electronics component is in communication with the one or more sensors via the fiber optic cable.

TECHNICAL FIELD

The present application relates to enabling measurement while drilling and logging while drilling functions in high temperature high pressure environments. Specifically, the present application relates to enabling measurement while drilling and logging while drilling in high temperature high pressure environments through optical fiber data transmission.

BACKGROUND

Measurement while drilling (MWD) and logging while drilling (LWD) tools are used to take measurements of certain downhole conditions during drilling operations. The measured conditions may include a location and orientation of the drill or well, information regarding the rock formation and its properties, temperature, and so forth. This data is collected by the MWD/LWD tools and transmitted to the surface to be analyzed. This allows operators to gauge conditions downhole and make effective operational decisions. However, current MWD/LWD tools are only suitable for use in environments having temperatures under 350° F., and tend to fail when subject to temperatures above 350° F.

This temperature limitation presents a challenge because many hydrocarbon resources exist in deeper levels of the earth which have high temperature high pressure (HTHP) environments. The existing MWD/LWD tools fail when they enter such depths. Thus, the remaining distance of the well to be drilled must be drilled blindly, meaning operators are no longer receiving information such as the location and orientation of the drill and other downhole conditions. This generates greater error in the location of the drilled well and risks missing the geological target. This is especially problematic when the desired location of the wellbore allows for small margin of error. Thus, it desirable to enable MWD/LWD functions in HTHP environments.

SUMMARY

In general, in one aspect, the disclosure relates to a method of drilling a wellbore. The method includes drilling a first portion of a well using a first drill string, and then pulling the first drill string out of the well. The method further includes inserting a lower drill string into the well. The lower drill string comprises a bottom hole assembly, a plurality of drill pipes, and a sensor system. The sensor system comprises one or more sensors coupled to a first connector. The method also includes lowering a fiber optic cable into the lower drill string. The fiber optic cable includes a second connector configured to mate with the first connector. Accordingly, the method includes mating the second connector with the first connector. The method also includes coupling the fiber optic cable to a MWD/LWD electronics system at an end of the fiber optic cable opposite the second connector. The electronics system is a part of an upper drill string, and the electronics system is in communication with the sensor system via the fiber optic cable. The method further includes coupling the upper drill string to the lower drill string forming a drill string assembly and drilling a second portion of the well.

In another aspect, the disclosure can generally relate to a method of monitoring conditions while drilling. The method includes detecting one or more drilling conditions via one or more sensors, and outputting one or more data signals corresponding to the one or more detected drilling conditions, in which the sensors are coupled to a lower drill string. The method further includes transmitting the one or more data signals from the one or more sensors to a first connector, in which the first connector is disposed within the lower drill string. The method also includes transmitting the one or more data signals from the first connector to a second connector, in which the second connector is coupled to the first connector. The method also includes transmitting the one or more data signals from the second connector to an electronics system via a fiber optic cable. The electronics system is disposed in an upper drill string.

In another aspect, the disclosure can generally relate to a drilling system with fiber optic communication. The drilling system includes a lower drill string and an upper drill string. The lower drill string includes a drill bit, a drive system coupled to the drill bit, at least one lower drill pipe coupled to the drive system, and a sensor system disposed in the at least one lower drill pipe. The sensor system includes one or more sensors and a first connector coupled to the one or more sensors. The upper drill string is coupled to the lower drill string and includes one or more upper drill pipes. The upper still string also includes a MWD/LWD electronics system coupled to the one or more upper drill pipes. The MWD/LWD electronics system includes an electronics component communicatively coupled to the first connector via a fiber optic cable. The electronics component is in communication with the one or more sensors via the fiber optic cable.

These and other aspects, objects, features, and embodiments will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate only example embodiments of the present disclosure, and are therefore not to be considered limiting of its scope, as the disclosures herein may admit to other equally effective embodiments. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or positions may be exaggerated to help visually convey such principles. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements. In one or more embodiments, one or more of the features shown in each of the figures may be omitted, added, repeated, and/or substituted. Accordingly, embodiments of the present disclosure should not be limited to the specific arrangements of components shown in these figures.

FIG. 1 illustrates a schematic diagram of a well site drilled using a fiber optic drilling system, in accordance with example embodiments of the present disclosure.

FIGS. 2a-2e illustrate different stages of drilling the well of FIG. 1, using an example embodiment of the methods and systems of the present disclosure.

FIG. 3 illustrates a detailed view of an example embodiment of a connector system used in a fiber optic drilling system, in accordance with example embodiments of the present disclosure.

FIG. 4 is a flow chart illustrating a method of drilling a well, in accordance with example embodiments of the present disclosure.

FIG. 5 is a flow chart illustrating a method of monitoring conditions while drilling, in accordance with example embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments directed to a system and method will now be described in detail with reference to the accompanying figures. Like, but not necessarily the same or identical, elements in the various figures are denoted by like reference numerals for consistency. In the following detailed description of the example embodiments, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure herein. However, it will be apparent to one of ordinary skill in the art that the example embodiments disclosed herein may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. The example embodiments illustrated herein include certain components that may be replaced by alternate or equivalent components in other example embodiments as will be apparent to one of ordinary skill in the art. One application of the systems and methods of the present disclosure is in the drilling of exploration and/or production wells. It is well known in the industry that specific techniques and equipment used in the drilling of individual wells may vary. For the sake of brevity, a general example of drilling equipment and environments are described herein. The examples are provided for context and not as a limitation on the application of the present disclosure. Rather, in practice, the systems and techniques presented herein can be adapted to fit the drilling of various types of wells and well conditions.

Referring now to the drawings, FIG. 1 illustrates a schematic diagram of a well site 100 drilled using a fiber optic drilling system 102, in accordance with example embodiments of the present disclosure. In certain example embodiments, and as illustrated, the fiber optic drilling system 102 (hereinafter “drilling system”) is used to drill a wellbore 108. In certain example embodiments, the wellbore 108 is formed in a subterranean formation 118 and coupled to a drilling rig 110 on a surface 112 of the formation 118. The formation 118 can include one or more of a number of formation types, including but not limited to shale, limestone, sandstone, clay, sand, and salt. The surface 112 may be ground level for an on-shore application or the sea floor for an off-shore application. In certain embodiments, a subterranean formation 118 can also include one or more reservoirs in which one or more resources (e.g., oil, gas, water, steam) are located.

The drilling system 102 includes a drill string assembly 106. In certain example embodiments, the drill string assembly 106 includes an upper drill string 120 and a lower drill string 122 coupled together at a coupling point 134. The upper drill string 120 includes a plurality of drill pipes coupled together linearly to make up the length of the upper drill string 120. The upper drill string 120 further includes a measurement while drilling (MWD) and/or logging while drilling (LWD) electronics component 124. The MWD/LWD electronics component 124 can comprise typical components for receiving and processing data, including one or more processors, a memory, and a communications interface. A power source 125 is electrically coupled to the MWD/LWD electronics component 124 and provides power to the MWD/LWD electronics component 124 and/or one or more sensors 126 via fiber optic cable 128. In certain example embodiments, the power source 125 comprises one or more batteries and/or a generator. In certain example embodiments, the lower drill string 122 includes a plurality of drill pipes coupled to a bottom hole assembly (BHA). In certain example embodiments, the BHA includes a drill bit 130 and a drive system 132, and one or more sensors 126. In certain example embodiments, the one or more sensors 126 are capable of functioning in a high temperature high pressure (HTHP) environment. In certain example embodiments, the one or more sensors 126 are communicably coupled to the MWD/LWD electronics component 124 via a fiber optic cable 128. Specifically, in certain such example embodiments, the one or more sensors 126 are communicably coupled to the MWD/LWD electronics component 124. The one or more sensors 126 are configured to detect one or more conditions, respectively. In certain example embodiments, the one or more sensors 126 include any combination of an acoustic sensor, a pressure sensor, a temperature sensor, a resistivity sensor, a gamma ray sensor, and an inclination azimuth sensor. Accordingly, the fiber optic cable 128 includes a fiber optic channel coupled to each sensor. Thus in certain example embodiments, the fiber optic cable 128 transmits a plurality of data signals and power.

In certain example embodiments, the MWD/LWD electronics component 124 receives the plurality of data signals via the fiber optic cable 128. The MWD/LWD electronics component 124 include a logic unit, such as one or more processors, which converts the data signals into binary digits, which are then transmitted to the surface 112 using mud pulse telemetry. In certain example embodiments, the mud pulse telemetry uses a fluid based binary coding transmission system such as combinatorial, Manchester encoding, split-phase, among others. The mud pulse telemetry signals are received and decoded by receivers at the surface 112. In certain example embodiments, the fiber optic cable 128 also delivers power to the one or more sensors 126. In certain example embodiments, the fiber optic cable 128 delivers power to the one or more sensors 126 from the MWD/LWD electronics component 124.

In certain example embodiments, the well 108, when fully drilled, includes a HTHP zone 142 and a standard zone 140. In certain example embodiments, the standard zone 140 may be 20,000 feet deep and/or have temperatures up to 350° F., and the HTHP zone 142 may be an additional 10,000 feet deep and/or have temperatures up to 500° F. The components of the lower drill string 122, including the drill bit 130, the drive system 132, and the one or more sensors 126, are disposed in the HTHP zone 142 of the well 108 and are thus rated to be able to withstand and function properly under such HTHP conditions. In certain example embodiments, the upper drill string 120 is kept in the standard zone 140 of the well 108 and does not enter the HTHP zone 142 of the well. The MWD/LWD electronics component 124 is a part of the upper drill string 120 and thus kept out of the HTHP zone 142. Therefore, the MWD/LWD electronics component 124 do not have to be rated for HTHP environment. However, because the one or more sensors 126 are able to detect conditions within the HTHP zone and transmit the data to the MWD/LWD electronics component 124 via the fiber optic cable 128, the MWD/LWD is able to measure and/or log conditions in the HTHP zone 142 without having to be in the HTHP zone 142.

FIGS. 2a-2e illustrate different stages of drilling the well 108, using an example embodiment of the methods and systems of the present disclosure. FIG. 2a illustrates the drilling of the standard zone 140 of the well 108. Referring to FIG. 2a , the standard zone 140 is drilled using a conventional drill string 202. After the standard zone 140 has been drilled, the conventional drill string 202 is removed from the hole. Next, referring to FIG. 2b , the lower drill string 122 of the drill string assembly is lowered into the well 108. In certain example embodiments, the lower drill string 122 includes a first connector 204 disposed therein. The first connector 204 is coupled to the one or more sensors 126 via one or more fiber optic channels 210.

Next, referring to FIG. 2c , the fiber optic cable 128 is lowered into lower drill string 122. In certain example embodiments, the fiber optic cable 128 includes a second connector 206 disposed at one end. The second connector 206 is configured to mate with the first connector 204 when it is lowered into the lower drill string 122. The mating of the first and second connectors 204, 206 puts the one or more sensors 126 in communication with the fiber optic cable 128. In certain example embodiments, the fiber optic cable 128 is lowered into the lower drill string 122 via a spool 208 until the second connector 206 mates with the first connector 204. In certain example embodiments, the fiber optic cable 128 includes a first end and a second end in which the first end is coupled to the second connector 206.

Referring to FIG. 2d , after the second connector 206 of the fiber optic cable 128 is coupled to the first connector 204 in the lower drill string 122, the second end of the optic cable 128, which is opposite the second connector 206, is coupled to the MWD/LWD electronics component 124 of the upper drill string 120. In certain example embodiments, the upper drill string 120 is above the surface 112 while the fiber optic cable 128 is coupled to the MWD/LWD electronics component 124. In certain example embodiments, after the fiber optic cable 128 is coupled to the MWD/LWD electronics component 124, the upper drill string 120 is coupled to the lower drill string 120 at the coupling point 134, forming the drill string assembly 106. In certain example embodiments, at this point, the one or more sensors 126 are communicably coupled to the MWD/LWD electronics component 124 via the fiber optic cable 128.

In certain example embodiments, the fiber optic cable 128 is substantially the length of the distance between the first connector 204 and the MWD/LWD electronics component 124. In certain example embodiment, the length of the fiber optic cable 128 is longer than the distance between the first connector 204 and the MWD/LWD electronics component 124. In certain example embodiments, the length of the optic cable 128 is at least as long as the distance between the first connector 204 and the MWD/LWD electronics component 124 and the excess length is determined based on an expected stretch of the lower drill string 122 during certain pulling functions such as tripping out of hole. In certain example embodiments, the length of the fiber optic cable 128 is long enough to accommodate such a stretch, which increases the distance between the first connector 204 and the MWD/LWD electronics component 124. After the optical cable 128 is coupled to both the first connector 204 and the MWD/LWD electronics component 124 and the upper drill string 120 is coupled to the lower drill string 122, the drill string assembly 106 is inserted into the wellbore 108 all the way to the bottom of the standard zone 140, which was previously drilled. Referring to FIG. 2e , the drill string assembly 106 is then used to drill the HTHP zone 142. During drilling of the HTHP zone 142, the one or more sensors 126 detect one or more conditions and transmit the data to the MWD/LWD electronics component 124 which measures and logs the drilling conditions.

FIG. 3 illustrates a detailed view of an example embodiment of the first connector 204 and the second connector 206. In certain example embodiments, the one or more sensors 126 include one or more LWD sensors 126 a. In certain example embodiments, the one or more LWD sensors 126 a are disposed on the sides of the lower drill string 122. In certain example embodiments, the first connector 204 is disposed in the middle of the lower drill string. The one or more LWD sensors 126 a are coupled to the first connector 204 via one or more fiber optic channels 210 running along the side of the lower drill string 122. In certain example embodiments, the first connector 204 includes a central plug receptacle 308 and a plurality of centralizers 302 extending from the central plug receptacle 308 to the sides of the lower drill string 122. The centralizers 302 keep the plug receptacle 308 centrally aligned. In certain example embodiments, the plug receptacle 308 includes a plurality of tiered connection points 304, in which each connection point provides a separate communication channel and is coupled to one of the sensors 126. In certain example embodiments, the one or more sensors 126 further includes at least one MWD sensor 126 b. In certain example embodiments, the at least one MWD sensor 126 b is disposed on the first connector 204 adjacent the central plug receptacle 308 such that the at least one MWD sensor 126 b is centrally aligned with the lower drill string 122. This allows the MWD sensor 126 b to detect location parameters most accurately.

In certain example embodiments, the second connector 206 which is coupled to the first end of the fiber optic cable 128 includes a central plug 310 and a plurality of centralizers 302 which keep the plug 310 centrally aligned. Specifically, the centralizers 302 keep the plug 310 centrally aligned as the second connector 206 is lowered into the lower drill string 122. Thus, the plug 310 is in alignment with the plug receptacle 308, allowing the plug 310 to mate with the plug receptacle 308 and form a mechanical and electrical connection. In certain example embodiments, the plug 310 includes a plurality of tiered connection points 306, each of which is electrically distinct and isolated from the others. Thus, when the plug 310 is coupled with the plug receptacle 308, each connection point 306 of the plug 310 is electrically coupled to the corresponding connection point 304 in the plug receptacle 308. The fiber optic cable 128 also includes a corresponding plurality of fiber optic channels, each of which corresponds to a connection point 306, 304. Thus, the signals transmitted from each of the one or more sensors 126 is distinctly communicated to the MWD/LWD electronics component 124.

In certain example embodiments, the first connector 204 and the second connector 206 are wet connectors. FIG. 3 and the above description of the first connector 204 and the second connector 206 is one example embodiment of what the first connector 204 and the second connector 206 can be. In practice, various types of connectors and alignment means can be used. For example, the two connectors 204, 206 can be aligned with each other magnetically, or through keying. In another example embodiments, the connectors 204, 206 have a plurality of contact plugs to provide the distinct connection paths. In another example embodiment, the first connector 204 and the second connector 206 can be reversed. In certain example embodiments, there is space around the first and second connectors 204, 206 which allows drilling fluid to traverse therethrough. In certain example embodiments, the one or more sensors 126 are disposed on or adjacent to the first connector 204 such that no fiber optic channel 210 or other wire is required to electrically couple the one or more sensors 126 to the first connector 204.

FIG. 4 is a flow chart illustrating a method of drilling a well, in accordance with example embodiments of the present disclosure. Specifically, the method 400 of FIG. 4 enables MWD/LWD functions while drilling in HTHP environments. In certain example embodiments, the method 400 includes drilling a first distance into a well using a first drill string (step 402). In certain example embodiments, the first distance into the well has a temperature and pressure profile suitable for a conventional drill string and conventional MWD/LWD tools. In certain example embodiments, the first drill string is a conventional drill string with conventional MWD/LWD tools. After the first distance of the well has been drilled, the first drill string is pulled out of the well (step 404). The method 400 further includes inserting a lower drill string into the well (step 406). The lower drill string comprises a bottom hole assembly, a plurality of drill pipes, and a sensor system. In certain example embodiments, the sensor system includes one or more MWD/LWD sensors coupled to a first connector. The sensors are rated to be able to withstand certain HTHP environments such as up to 500° F. The method 400 further includes lowering a fiber optic cable into the lower drill string until the fiber optic cable couples to the first connector of the sensor system (step 408).

In certain example embodiments, the fiber optic cable includes a second connector which mates with the first connector, thereby putting the fiber optic cable in communication with the sensors. The method 400 further includes coupling the fiber optic cable to a MWD/LWD electronics component at an end of the fiber optic cable opposite the second connector (step 410). The MWD/LWD electronics component is a part of an upper drill string. Thus, the sensors in the lower drill string are communicably coupled to the MWD/LWD electronics component in the upper drill string. The method 400 further includes coupling the upper drill string to the lower drill string, forming a drill string assembly (step 412). In certain example embodiments, the method 400 further includes drilling a second distance of the well using the drill string assembly. In certain example embodiments, the second distance of the well is in a region having HTHP conditions. In certain example embodiments, the length of the lower drill string is at least as long as the second distance. Thus, the MWD/LWD electronics component are kept above the well region having HTHP conditions while still being able to collect data from the HTHP region via the sensors in the lower drill string.

FIG. 5 illustrates a method of monitoring conditions while drilling, in accordance with example embodiments of the present disclosure. The method 500 includes detecting one or more drilling conditions via one or more sensors (step 502). The method 500 further includes outputting one or more data signals corresponding to the one or more detected drilling conditions (step 504). In certain example embodiments, the sensors are coupled to a lower drill string. The method 500 also includes transmitting the one or more data signals from the one or more sensors to a first connector (step 506) and providing power to the one or more sensors in the lower drill string. In certain example embodiments, the first connector disposed within the lower drill string. The method 500 further includes transmitting the one or more signals from the first connector to a second connector (step 508). In certain example embodiments, the second connector is coupled to the first connector. The method 500 also includes transmitting the one or more signals from the second connector to a MWD/LWD electronics systems via a fiber optic cable (step 510). In certain example embodiments, the MWD/LWD electronics system is disposed in an upper drill string. In certain example embodiments, the method 500 further includes converting the one or more signals into one or more mud pulse signals (step 512) and transmitting the data to the surface where it can be analyzed.

Although embodiments described herein are made with reference to example embodiments, it should be appreciated by those skilled in the art that various modifications are well within the scope and spirit of this disclosure. Those skilled in the art will appreciate that the example embodiments described herein are not limited to any specifically discussed application and that the embodiments described herein are illustrative and not restrictive. From the description of the example embodiments, equivalents of the elements shown therein will suggest themselves to those skilled in the art, and ways of constructing other embodiments using the present disclosure will suggest themselves to practitioners of the art. Therefore, the scope of the example embodiments is not limited herein. 

What is claimed is:
 1. A method of drilling a wellbore, comprising: drilling a first portion of a well using a first drill string; pulling the first drill string out of the well; inserting a lower drill string into the well, wherein the lower drill string comprises a bottom hole assembly, a plurality of drill pipes, and a sensor system, wherein the sensor system comprises one or more sensors coupled to a first connector; lowering a fiber optic cable into the lower drill string, wherein the fiber optic cable comprises a second connector configured to mate with the first connector; mating the second connector with the first connector; coupling the fiber optic cable to a MWD/LWD electronics system at an end of the fiber optic cable opposite the second connector, wherein the electronics system is a part of an upper drill string, and wherein the electronics system is in communication with the sensor system via the fiber optic cable; coupling the upper drill string to the lower drill string forming a drill string assembly; and drilling a second portion of the well.
 2. The method of claim 1, further comprising: sensing one or more conditions in the second portion of the well by the sensor system; and transmitting one or more data signals corresponding to the one or more conditions from the sensor system to the MWD/LWD electronics system via the fiber optic cable.
 3. The method of claim 1, wherein second portion of the well is in a high temperature high pressure environment.
 4. The method of claim 1, wherein the MWD/LWD electronics system remains in the first portion of the well while drilling the second portion of the well.
 5. The method of claim 1, wherein the sensor system comprises any combination of an acoustic sensor, a pressure sensor, a temperature sensor, a resistivity sensor, a gamma ray sensor, and an inclination azimuth sensor.
 6. The method of claim 1, wherein the first connector and the second connector are wet connectors.
 7. A method of monitoring conditions while drilling, comprising: detecting one or more drilling conditions via one or more sensors; outputting one or more data signals corresponding to the one or more detected drilling conditions, wherein the sensors are coupled to a lower drill string; transmitting the one or more data signals from the one or more sensors to a first connector, the first connector disposed within the lower drill string; transmitting the one or more data signals from the first connector to a second connector, the second connector coupled to the first connector; and transmitting the one or more data signals from the second connector to a MWD/LWD electronics system via a fiber optic cable, the electronics system disposed in an upper drill string.
 8. The method of claim 7, further comprising: converting, by a processor in the electronics system, the one or more data signals into one or more mud pulse signals; and transmitting the one or more mud pulse signals to a receiver.
 9. The method of claim 7, wherein the lower drill string and the one or more sensors is disposed within a high temperature high pressure zone of a well.
 10. The method of claim 8, wherein the upper drill string and the MWD/LWD electronics system remains out of the high temperature high pressure zone.
 11. The method of claim 7, wherein the one or more sensors are rated to function properly in environments having temperatures up to 500° F.
 12. The method of claim 11, wherein the one or more sensors comprise any combination of an acoustic sensor, a pressure sensor, a temperature sensor, a resistivity sensor, a gamma ray sensor, and an inclination azimuth sensor.
 13. The method of claim 11, wherein the fiber optic cable comprises a plurality of distinct fiber optic channels, and is configured to carry a plurality of distinct data signals.
 14. The method of claim 11, comprising: detecting conditions of a high temperature high pressure well zone from outside of the high temperature high pressure well zone via the one or more sensors disposed within the high temperature high pressure well zone.
 15. A drilling system with fiber optic communication, comprising: a lower drill string comprising: a drill bit; a drive system coupled to the drill bit; at least one lower drill pipe coupled to the drive system; a sensor system disposed in the at least one lower drill pipe, the sensor system comprising one or more sensors and a first connector coupled to the one or more sensors; and an upper drill string coupled to the lower drill string, the upper drill string comprising: one or more upper drill pipes, and a MWD/LWD electronics system coupled to the one or more upper drill pipes, the MWD/LWD electronics system comprising an electronics component, wherein the electronics component is communicatively coupled to the first connector via a fiber optic cable, wherein the electronics component is in communication with the one or more sensors via the fiber optic cable.
 16. The drilling system of claim 15, wherein the one or more sensors are rated to function properly in an environment having temperatures up to 500°.
 17. The drilling system of claim 15, wherein the one or more sensors comprise any combination of an acoustic sensor, a pressure sensor, a temperature sensor, a resistivity sensor, a gamma ray sensor, and an inclination azimuth sensor.
 18. The drilling system of claim 15, wherein the first connector and the second connector are centrally disposed within the lower drill string.
 19. The drilling system of claim 15, wherein the fiber optic cable comprises a plurality of distinct fiber optic channels, and is configured to carry a plurality of distinct data signals.
 20. The drilling system of claim 15, wherein the upper drill string and the MWD/LWD electronics system remains out of a high temperature high pressure well zone while the lower drill string and sensor system are in the high temperature high pressure well zone. 